When you have had one or more unexplained blood clots in a vein or artery; when you have had recurrent miscarriages, especially in the second and third trimesters

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

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The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

Beta-2 glycoprotein 1 antibody is an autoantibody that is associated with inappropriate blood clotting. This test detects and measures one or more classes (IgG, IgM, or IgA) of beta-2 glycoprotein 1 antibodies.

Beta-2 glycoprotein antibody is considered one of the primary autoantibodies called antiphospholipid antibodies that mistakenly target the body's own lipid-proteins (phospholipids) found in the outermost layer of cells (cell membranes) and platelets. This test is often ordered along with those for the other antiphospholipid antibodies, cardiolipin antibody and lupus anticoagulant.

Antiphospholipid antibodies interfere with the body's blood clotting process in a way that is not fully understood. Their presence increases a person's risk of developing inappropriate blood clots (thrombi) in both arteries and veins. Antiphospholipid antibodies are most frequently seen in people with the autoimmune disorder called antiphospholipid syndrome (APS), which is associated with blood clots (thrombotic episodes), a low platelet count (thrombocytopenia), or with pregnancy complications such as pre-eclampsia and recurrent miscarriages, especially in the second and third trimesters.

Antiphospholipid antibodies, including beta-2 glycoprotein anitboides, are associated with excessive clotting. They interfere with the body's blood clotting process in a way that is not fully understood. (See the "What is being tested?" section for more.)

As beta-2 glycoprotein 1 antibody is less common than the other antiphospholipid antibodies, it may be ordered as a follow-up to those tests to provide a health practitioner with additional information. However, beta 2 glycoprotein 1 antibodies have been reported to be more specific (but less sensitive) than cardiolipin antibodies for the diagnosis of APS.

Laboratory tests can detect three different classes of these autoantibodies: IgG, IgM, and IgA. If all three of the initial antiphospholipid antibody tests for the IgG and IgM classes are negative but APS is still suspected, then the IgA class of these antibodies may be tested, along with other less common antiphospholipid antibodies, such as anti-phosphatidylserine and anti-prothrombin. However, the value of testing for the IgA class of antiphospholipid antibodies remains controversial. According to the international consensus statement on APS, the presence of the IgA class (either anticardiolipin antibodies or beta-2 glycoprotein 1 antibodies) does not fulfill laboratory criteria for APS diagnosis.

If a beta-2 glycoprotein 1 antibody is detected, the same test will be repeated about 12 weeks later to determine whether its presence is persistent or temporary. If a person with an autoimmune disorder tests negative for antiphospholipid antibodies, testing may be repeated at a later time to determine if the person has begun to produce antibodies, as they may develop at any time in the course of disease.

Beta-2 glycoprotein 1 antibody tests and other antiphospholipid antibody testing may be ordered when a person's symptoms suggest a blood clot in a vein or artery. Symptoms may include pain and swelling in the extremities, shortness of breath, and headaches.

Beta-2 glycoprotein 1 antibody tests may also be ordered when a woman has had recurrent miscarriages or when a person has signs and symptoms of antiphospholipid syndrome (APS), such as:

A positive beta-2 glycoprotein 1 antibody test may indicate that the person has antiphospholipid syndrome (APS), as they are most frequently seen with the condition. Current diagnostic criteria for APS are based upon both clinical findings and the persistent presence of one or more antiphospholipid antibodies. If a high level of beta-2 glycoprotein 1 antibody is detected initially and then again 12 weeks later in a person with signs of APS, then it is likely that the person has the disorder. This is especially true if other antiphospholipid antibodies are also detected.

If a person is negative for beta-2 glycoprotein 1 antibodies but positive for other antiphospholipid antibodies and has signs and symptoms, then that person also likely has APS.

If the test is weakly to moderately positive for beta-2 glycoprotein 1 antibodies and weakly positive or negative for other antiphospholipid antibodies, then the antibody presence may be due to a condition other than APS. If subsequent testing is negative, then it is likely that the antibodies were temporary. This may be seen with an acute infection.

A single positive beta-2 glycoprotein 1 antibody result is not diagnostic of APS, and a negative result does not rule out antiphospholipid antibody development. They just indicate the presence or absence of the antibody at the time of testing. That is why a diagnosis of APS requires clinical symptoms plus at least two positive tests for an antiphospholipid antibody at least 12 weeks apart.

Not necessarily. They represent a risk factor but cannot predict whether an individual person will have recurrent blood clots. And, if a person does, the presence of the antibodies cannot predict the frequency or severity of clotting.

Yes, this is an important part of your medical history. Your doctor needs this information even if you don't have symptoms in order to tailor any procedures or medical treatment plans around this risk factor.

(Reviewed 2010 December 15). Learning About Antiphospholipid Syndrome (APS). National Human Genome Research Institute. Available online at http://www.genome.gov/17516396 through http://www.genome.gov. Accessed February 2015.

(Reviewed 2010 December 15). Learning About Antiphospholipid Syndrome (APS). National Human Genome Research Institute [On-line information]. Available online at http://www.genome.gov/17516396 through http://www.genome.gov. Accessed March 2011.

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